Atlantis returns to its home port at Kennedy Space Center. Photo: NASA

Space shuttles Atlantis and Columbia made it back to Florida's Space Coast on Monday after lengthy cross-country ferry flights from California, but there wasn't enough parking spots at Kennedy Space Center for both spaceplanes and their carrier aircraft.

The spectacle of two stubby-winged spaceships riding piggyback atop jumbo jets caused quite a stur along the coastline as the shuttles buzzed over residents and tourists gazing skyward from chilly beaches. The arrivals occurred less than four hours apart.

It was the first time in the history of shuttle program that two ferry flights have occurred simultaneously.

Atlantis touched down at KSC's Shuttle Landing Facility at 10:56 a.m. EST (1556 GMT), concluding its trek from Edwards Air Force Base in California that began last Thursday.

The shuttle glided to a landing at the Mojave Desert base on February 20 to cap its 23rd trip into space -- a 12-day, 21-hour, 5.3-million mile voyage that delivered the U.S. Destiny laboratory to the international space station.

Following its departure atop one of NASA's modified 747 carrier jets, Atlantis was flown to Altus Air Force Base in Oklahoma last Thursday where it remained until Sunday because unacceptable flying weather prevented a continuation toward KSC. A break did come Sunday and Atlantis was flown to Barksdale AFB in Louisiana for refueling and then on to Eglin AFB in Florida for an overnight stop.

Columbia, meanwhile, is not exactly back home yet. The oldest shuttle can almost see its final destination from the runway that greeted the other carrier aircraft at 2:37 p.m. EST (1937 GMT) Monday.

An aerial view Columbia shortly after departure from Palmdale shows the shuttle's new page job with its historical wing markings removed and replaced with the NASA Meatball, flag and vehicle name. This change makes Columbia appear more similar to its sisterships. Photo: NASA

Because launch support aircraft and equipment have been moved into position at KSC's runway ramp in preparation for Thursday's scheduled liftoff of Discovery, there isn't enough room for both 747s.

As a result, NASA diverted Columbia to neighboring Cape Canaveral Air Force Station's Skid Strip, just a few miles from KSC.

Columbia has been away from Florida for 17 months undergoing a major overhaul and tune up at the Boeing shuttle assembly plant in Palmdale, California -- about 25 miles from Edwards Air Force Base in the Golden State's Antelope Valley.

Like Atlantis, a brief window of favorable weather allowed Columbia to depart California last Thursday. Its stop-over that night, which became extended by the same bad weather plaguing Atlantis, was Dyess AFB in Texas.

NASA did not want both shuttles to fly together and make stops at the same locations due to security concerns.

Columbia's piggyback trek resumed Monday and brought the shuttle to Cape Canaveral.

The Shuttle Carrier Aircraft with Columbia after arriving at Cape Canaveral. Photo: NASA

Once Atlantis is removed from atop its carrier jet, which could be held up due to high winds, Columbia will take a short ride to KSC for demating from the 747. That hop is targeted for Wednesday.

Atlantis is slated for another space mission in June to attach the airlock to the space station. Columbia's next launch is targeted for late November on a flight that will either feature a Spacehab scientific research module or the fourth servicing of the Hubble Space Telescope. Shuttle program officials have not yet settled on which payload will be flown.